For Jewish religious thinkers in our time, the question "why observe mitzvot?" has become a central and critical concern. Some answers echo earlier periods, some are new.

A concern, bordering on obsession, with the commandments is one of the earmarks not only of traditional Judaism, but of its progressive branches as well.
Each of the [non-Orthodox] denominations defines itself in large part by its relationship to the mitzvot and the laws that govern them. Abraham Joshua Heschel explains the centrality of the mitzvot brilliantly, contrasting their central place in Jewish thought with the much less important role of ceremonies:

Ceremonies, whether in the form of things or in the form of actions, are required by custom and convention; mitzvot are required by Torah. Ceremonies are relevant to man; mitzvot are relevant to God. Ceremonies are folkways; mitzvot are ways to God. Ceremonies are expressions of the human mind; what they express and their power to express depend on a mental act of man; their significance is gone when man ceases to be responsive to them. Mitzvot, on the other hand, are expressions or interpretations of the will of God. While they are meaningful to man, the source of their meaning is not in the understanding of man but in the love of God. Ceremonies are created for the purpose of signifying; mitzvot were given for the purpose of sanctifying. Their function: to refine, ennoble, to sanctify man. They confer holiness upon us, whether or not we know exactly what they signify. (From: “Toward an Understanding of Halakhah” in Moral Grandeur and Spiritual Audacity)

Heschel cuts to the heart of another important question: why observe the mitzvot? For him it is an existential question. To act in the right way is “to refine, ennoble, or sanctify” humanity. We “confer holiness” upon ourselves by expressing our love—our trust, given that we may not even know what these acts mean—of God. In that statement Heschel echoes the word of the Rav, who seventeen hundred years earlier said that the purpose of the mitzvot was “to refine humanity.”

Of course, other commentators have offered different explanations. In the Torah, the rationale is blunt, almost brutal: humanity is to follow the commandments or it will suffer divine punishment. The punishment/reward schema is certainly an element that comes into play in Jewish thought, particularly in understanding the nature of the covenant between God and the forefathers, and in the writings of the Orthodox rabbinate past and present. After all, there is a midrash that says that when God asked the Israelites if they would accept the commandments, the Almighty held Mount Sinai in mid-air over their heads and made the choice even easier: “Say yes, or I drop the mountain on you.” The Talmud says that one “who performs one mitzvah receives good things.”

George Robinson, author of Essential Judaism, is the recipient of a Simon Rockower Award for excellence in Jewish journalism from the American Jewish Press Association. His writing has appeared in The New York Times, The Washington Post, Newsday, Jewish Week, and The Detroit Jewish News.